Securing of stability during reconstruction of buildings
Additional building to the Viktoria company furniture store in Tabor


When reconstructing buildings, it can often happen that their construction and subsoil does not bear the overstress formed due to the demolition works (increase of openings within the construction, overloading with additional storey and etc). During the reconstruction of the Viktoria store in Tabor the following findings were made:

• existing ceiling between the cellar and ground floor forms an arch construction. The distance in between the supporting I profiles was 1m, dimensions of the I profiles were not known
• quality of the brick wall in the cellar was unknown, the whole cellar area was very humid

Results of the statical and geotechnical judgments made before the planned reconstruction showed showed teh following ore the planned reconstruction.

• The subsoil can bear increased load from the post bellow the foundation. In order to secure a good contact of the subsoil with the foundation, performance of grouting was recommended.
• Tension in the post: (619,72 / 0,55 = 1126 kPa). This tension is too high when not knowing the quality and the state of the brick wall. It was therefore recommended to build in supporting frames.
• In order to safely transfer the loading into the subsoil, the subsoil was reinforced by construction of micropiles underneath the foundation in the most loaded places. The proposed method does not increase the average tension in the foundation bottom, but forms, due to re-distribution of the loading local extremes, which are safely eliminated by the micropiles.
• Tension underneath the distribution element (371,83 / (20 X 55) = 0,34 kNcm-2 . This tension could not be allowed at the brick ceiling of the cellar, therefore it was necessary to join and wedge the U profiles in the basement to the distribution element of the ground level.

Description of the performed works

Grouting and anchoring works were performed using the Geopur grouting system.

• Anchoring of the U profiles to the mansonry
  In order to eliminate the eccentric loading of the steel construction, we performed in the cellar connection of the U profiles with the mansonry using grouting anchors. The anchors of 1,5 m lengths were drilled through masonry and drilled further into the soil. After their installation they were grouted with polyurethane resin Geopur 082/600 and finally fitted with screws assembled to the anchor. A total of 8 anchors were installed.
• Anchoring of U profiles at the cellar ground - micropiles
  anchoring of the U profile to the cellar ground was made similarly – with micropiles and anchoring. The length of the anchors was 1,5 m. The U profile was grouted and secured with a screw. A total of 8 anchors were drilled into the subsoil. Geopur 082/600 was used as a grouting material.
• Under-grouting of the foundation
  In order to secure a good contact of the foundation with the subsoil under-grouting of the foundation was performed. A total of 6 drillings of 0,6 m length and 14 mm diameter were drilled under the wall foundation. The drillings were drilled diagonally through the cellar ground and the masonry into the foundation bottom. Geopur 082/600 grouting material was used.